An image reading apparatus is described (U.S. Pat. No. 6,617,590) which includes three laser sources, a scanning mechanism for scanning a surface with a laser beam emitted from the laser sources, a light detector and a confocal optical system for leading light emitted from the image carrier to the light detector. The apparatus makes provision for a number of relevant detection techniques such as microarray imaging, autoradiographic imaging, chemiluminescent imaging and more. It includes a confocal switching member having pinholes of different diameters and disposed between the confocal optical system and the light detector. A drawback of the above described apparatus is that chromatic aberrations of the confocal lens are neglected thereby limiting simultaneous multi-color detection.
Fluorescence is a phenomenon that is used routinely in life science research. Fluorescent probes and conjugations are used extensively to trace the whereabouts of cellular components and protein localization, and to detect particular components e.g. biomolecules in complex biomolecular assemblies, including live cells, with exquisite sensitivity and selectivity.
A fluorescent probe is a fluorophore designed to localize within a specific region of a biological specimen or to respond to a specific stimulus. Multicolor labeling experiments entail the deliberate introduction of two or more probes to monitor different biochemical functions simultaneously. This technique has major applications in analytic techniques such as flow cytometry, DNA sequencing, fluorescence in situ hybridization (FISH), fluorescence microscopy, fluorescence spectroscopy, fluorescence resonance energy transfer (FRET), fluorescence recovery after photobleaching (FRAP), etc.